Cruncher: A robotic toy dinosaur dissection

When my children got these interesting and very obnoxious toy dinosaurs last year, I could barely contain my excitement. I knew that one day, they would be on my work bench giving up their secrets. Cruncher is a fairly recent addition to the robotic animal trend that we’ve been seeing the past few years. Imbued with a personality that is a mixture of T-Rex, beagle, and loudmouth jerk, he’s every kids idea of a perfect pet.

A quick review:

As the commercial above shows, he has several abilities such as responding to physical stimulus, detecting obstacles, responding to audio stimulus, and repeating a series of actions that he is put through. While those features might technically be possible, my boys found that most of them worked too poorly to really be used. He didn’t do much following, the “guard dog” setting was completely un-predictable, he did not “come when called”, he certainly did not play catch, but the kids found him hilarious. You could “program” him to do different actions by posing him in different ways for up to 30 different actions. In our house, however, it usually just turned into a string of 30 farts (the action he does if you lift his tail).

I didn’t purchase this, so I’m not sure what the actual cost was. They’re currently $60 on amazon. It was a fairly amusing toy though and the kids and dogs enjoyed it thoroughly.

The dissection:

One of the crunchers was sacrificed to the dogs earlier this year. It wasn’t really mourned, as it was the older of my sons and he had been dying to see the insides anyway. The younger son, however, was very protective of his and I only recently managed to talk him into letting me document the innards. He will be happy to know that cruncher is completely re-assembled and working.

Here you can see the full shot of the insides. Toward the top rear are the motor drivers and the control board. Up front we see the front facing sensors, steering servo, drive system, and neck turning motor.

Cruncher’s neck is a soft flexible material. It is glued to both halves of the body as well as the back of the head, preventing disassembly. Since this cruncher needed to be re-assembled when I was finished I had to pull the “skin” away while carefully cutting at the glued edge. When I was finished and he was all back together, I simply glued it back in place.

Here’s a somewhat closer look at the internal layout. At the base of the neck you can see the board that has the position sensor for the neck. Below that, on his chest are a pair of sensors. I’m not sure what they are, I’m guessing something for obstacle avoidance. I did not remove them for inspection.

Here’s another view of those sensors in cruncher’s chest. Could they be ultrasonic?

Here you can see the motor drivers and control board. They aren’t fastened to anything, just relying on the mass of wires to hold them in place.

Control board. Black blobs on front and back, no surprises there.

I suspect this is the motor driver. Looks like it is all there. You should, in theory, be able to replace the control board and still use this motor driver board.

If you look real close, you can see the tail switch, a.k.a. the fart switch.

A better view of one of the body halves. You can see the assembly that moves the arms and legs as well as a speaker and microphone. The arms and legs are purely aesthetic. They have no sensors and don’t really aide cruncher in any way.

The keypad on his collar. Here’s where you set the mode he’s in. For an 8 year old, this ended up not being very intuitive. If you hold the button, it toggles between two modes, however there’s really no way to know which mode he’s in at any given time. Since there are 8 possibilities, you just have to wait and see what he starts to do.

Here’s the neck assembly. It uses a single motor to extend the neck and, using a small lever that catches on the jaw, open/close the mouth. They really use this well as you can see in the commercials, this motion is what makes him talk, roar, and chomp. Upon closer inspection, I found that there is only a single item in his nostril that looks like an IR LED. I’m not sure how they’re utilizing it. He also has a button on the top of his head and a button on his bottom lip.

I’m hoping, one day, to get a chance to gut this guy and use him as the platform to learn more about some robotics. As I’ve said many times before, I’m not as capable as many of the other writers and most of our readers. I won’t be reverse engineering anything here. I would probably just start with my own micro controller to drive the motors and use the sensors. I will, however, have to wait till my 6 year old gives the OK.